If it is the compressor, NO you cannot repair it, You would have to get some one to do it, All the refrigerant needs to be removed, and then replaced, Its like the gas safe, Yo have to specially quallified to use the refrigerant.
If the unit is auto defrost, Might be the defrost htr, at fault, in which case you could repair it your self, You would need a test meter to find out.
SD
August 2011